Ruler, Thermometer and Stopwatch

Ruler

A metre rule has sensitivity or accuracy accuracy of 1mm.
Precaution to be taken when using ruler

1. Make sure that the object is in contact with the ruler.
2. Avoid parallax error.
3. Avoid zero error and end error.

Thermometer

There are 2 types of mercury thermometer

1. Thermometers of range -10^oC – 110^oC with accuracy 1^oC.
2. Thermometers of range 0^oC – 360^oC with accuracy 2^oC.

Precaution to be taken when using a thermometer

1. Make sure that the temperature measured does not exceed the measuring range.
2. When measuring the temperature of a liquid
   
   1. immerse the bulb fully in the liquid
   2. stir the liquid so that the temperature in the liquid is uniform
   3. do not stir the liquid vigorously to avoid breaking the thermometer

Stopwatch

There are 2 types of stopwatches

1. analogue stopwatches of sensitivity 0.1s or 0.2s
2. digital stopwatches of sensitivity 0.01s.

The sensitivity of a stopwatch depends on the reaction time of the user.